DESCRIPTION: (provided by the applicant) The purpose of this K02 application is to seek salary support for scientific career development of the PI at the Dept. Pharmacology of Univ. Minnesota Medical School. The PI was trained in molecular biology and genetics with special focus on interaction of hormone nuclear receptors and transcription factors. She has initiated a research project (DA-11190) aimed to study regulatory mechanisms for kappa opioid receptor (KOR) gene regulation. In order to develop her sceintific career along the line of drug abuse research and perform several experiments described in this project, she plans to devote more time into her research and receive further training in developmental neurobiology and opioid pharmacology. The project proposed is based upon the currently funded R01 to examine several important regulatory mechanisms underlying KOR gene expression. Three aims are proposed to address two fundamental problems in KOR gene regulation: transcription and post-transcriptional mechanisms for controlling KOR expression. Three aims are: 1)To Study Transcriptional Regulation of Mouse KOR Gene, 2) To Study Post-transcriptional Regulation of Mouse KOR Expression and 3) Transgenic Mouse Models to Study KOR Ontogeny and Regulation. The first aim will address transcriptional control by focusing on a retinoic acid (RA)-regulated silencer element located in intron 1 of the gene, and the positive mechanisms regulating promoters 1 and 2. The mechanisms underlying histone deacetylation on KOR promoters as a result of retinoid depletion will be addressed. Protein factors responsible for the activation of KOR gene in KOR neurons will be identified. An embryonic cell line P19 that is capable of differentiation into various cell lineages including KOR neurons and expresses KOR in an RA-regulated manner will be used. In the second aim, mRNA transport and protein translation efficiency will be examined in relation to the cell- and tissue type-specificity of KOR expression. The information gathered from aims 1 and 2 deals with KOR regulation in vitro. The third aim is to confirm and correct the information generated from in vitro models by using transgenic mouse models. These genetic studies will answer whether and how pharmacological problems, such as opioid addiction and tolerance, may be related to the endocrine system such as retinoid status and the homeostatic control of opioid receptor gene activity. The granting of this award will enable the PI to devote more time into her research projects and take leave of absence to receive training. This award is essential for the PI?s career development as a more productive and contributing scientist in the field of drug abuse research.